[Gem930]

Ive had my coach (639) raised to replace the Aquahot and generator exhaust system.  The front and mains were on heavy duty ramps and the body was cribbed with jack stands. The tags were not raised and still resting on the ground as the mains were only raised about 5".  It sat like that for sever weeks as I ended up having to completely rebuild the entire aquahot (unfortunately not just the exhaust). Anyway, I pulled the coach out and drove about 1/2 mile when the passsenger side tag locked up.  I park the coach and called Newell for advice.  They immediatley asked if the coach had been sitting and said the brakes can get stuck and told me how to cage the brake.  I went back with the 1' ( I think) socket and backed the bolt out of the brake chamber.  I was not sure how far to back it out and did not want it to fall completely out.  After backing the bolt out with the ratchet it started to spin freely.  I backed it out by hand until it got tight.  I then put the socket back on it a made probably 8 to 10 complete 360 degree turns.  The wheel was still locked up.  I did a few more turns and same thing.  I then played with the tag weight increase/ decrease button and it finally started to turn.  I got the coach home, but not sure where to start.  This senerio does not sound like the brake getting "stuck" as it rolled fine for 1/2 mile before locking up.  Not sure why the tag weight button would change thinkgs aside from maybe applying enought weight to turn a still partially stuck brake.  Any ideas????

[Richard]

A couple of things to look for. I think Newell also put the stop brake or spring brake on the tags by Coach 639. That brake requires air pressure to release it. When you press the Stop brake yellow button, you actually start air to the spring loaded brake chamber. If you compromised the air to the spring brake chamber because the hose cracked or pulled loose while the tag was hanging down, then it would explain what is happening.

So how to check? Chock the wheels. With engine off to kill the noise. Push the Stop brake button in. If you have a leak you should hear it.

If no leak, then jack up the tag wheel. What happens when you try to turn the wheel by hand? If it doesn’t spin by hand, then you will have to take the wheel off to get a better look at what is going on with the disc and the caliper.

On most spring brakes, there is a special wrench that rides in a clip on the brake that is inserted into the center hole of the spring brake chamber to cage it. When you cage the brake you are manually compressing the spring that actuates the STOP brake. You are doing the same thing that happens with air pressure when you release the STOP brake. What ever you do, DO NOT take the band off the spring brake chamber to see what is going on. There is enough stored energy in the spring to really hurt you.

[bikestuff]

This is for coaches with disc brakes only.

Could this have anything to do with pin that the caliper rides on? A little rubber boot protects the slide pin from road grit and if the boot fails, then the grit can get onto that pin and cause the brakes to “stick” on.

I had this happen twice. The symptom is that you start up like normal and after you have been on the road 10 -30 miles, the brakes heat up enough to produce smoke and you smell the problem before you feel the problem.

I am just throwing this out there in case it causes more experienced folks to chime in.

[cwl1979]

Have you checked fluid level in the hub? Caging the brake would allow it to roll freely unless the caliper was bound up. Might take the wheel off and inspect the brake. Might need new pads. Heavy disks seem to wear uneven in my experience. Unless meticulously maintained.

[Gem930]

Thanks for the replys.

I pulled the wheel and the brake chamber (from the bolts, not the clamp). The caliper is still locked up. I tried to pull the pads out, no go. It appears the orange silcone bellows are completely extednded. I tried turning the splined shaft that appears to be some kind of adjuster, but it is completely stuck as well. Thinking might be time to just replace the entire caliper???

[Gem930]

Well, i got the caliper off! What a nightmare. The adjuster wheel was completely rusted up. Not sure how it complete extended itself out prior to rusting up, but it did. I ended up having to soak the entire thing in WD-40 and hammer the caliper off the rotor with an 8 lb sledge! I'm going to just replace the caliper and call it good with two new tag brakes and a lighter wallet.

[Richard]

You can get them from prevost parts if needed.

[Richard]

Oh yeah. I think it’s 14mm. I have used an impact gun and a 14 mm hex to remove the slide pin bushings without removing the caliper.

[Jack Houpe]

I've done this job on another persons coach and yes sir it's not easy although I did have them there to remove and reinstall the wheel, they were having the same problem with the tag axle brake dragging. Glad you got it fixed and shared with the rest of us, Kroil is amazing product and if you don't have a can of it I highly recommend buying one for the future.